CORRECT DIAGNOSIS:
Dermatomyositis + systemic sclerosis
DISCUSSION:
This case demonstrates findings consistent with both dermatomyositis and systemic sclerosis, which are both autoimmune connective tissue disorders that can have a wide range of clinical and serologic findings. Our patient presented with DM findings including classic rash, Gottron’s papules, proximal muscle weakness, fatigue, weight loss. She did have an unusual presentation of cutaneous ulcers over shoulders and extremities as well as digital ulcers that are less likely seen in dermatomyositis and more frequently seen in systemic sclerosis and other vasculitides. Our patient did have an initial elevated ESR, ALT/AST, and aldolase consistent with findings of DM. Interestingly enough she also had a positive anti-myeloperoxidase antibody but largely negative autoantibody panel otherwise.
In a case report by Ahmed et al, they presented a case of seronegative dermatomyositis presenting with features of anti-MDA5 subtype. The presence of vascular injury is more commonly associated with DM subtype positive for anti-MDA5 antibody. Anti-MDA5 DM is a subtype of DM Sith a characteristic mucocutaneous phenotype, exhibiting punched-out cutaneous ulcers in up to 82% of patients, with predilection for digital pulp, periungual region, MCP and interphalangeal joints, elbows, and knees
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